1. Field of the Invention
This invention relates to a new and useful process for recovering oil from oil shale containing kerogen, a solid organic, primarily hydrocarbon, material having a high molecular weight, i.e., greater than about 3,000 grams/mole which comprises about 10 to about 30 percent by weight of oil shale. The percentage recovery, as oil, of the organic matter originally present in the oil shale is low by most methods known in the art. Even the best operations result in relative high conversion of kerogen to carbon and permanent gases, which are of low economic value compared to liquid fuels. Consequently, a need exists for a simple process for recovering oil from oil shale which results in a high yield of liquid product. Accordingly, the present invention provides a higher yield of liquid product by a process for recovering oil from oil shale containing kerogen which comprises contacting said oil shale with steam having a partial pressure of at least about 600 psia (4.3MPa) but no greater than about 3000 psia (20.8 MPa) at a reaction temperature ranging from about 300.degree. C. to about 500.degree. C. for a period of time ranging from about 0.5 to about 6 hours.
2. Description of the Prior Art
U.S. Pat. No. 3,051,644 to L. D. Friedman teaches the recovery of oil from oil shale by subjecting a pumpable water slurry of shale to a jiggling-bed reactor at high temperature (700.degree. to 900.degree. F.) and pressure (1000 to 3000 psig) for long periods of time (20 minutes to 6 hours) (column 1, lines 3-32). An elongated heating zone of restricted cross-sectional area is used as a preheater. In the preheater, water is completely vaporized to form steam and the latter moves at a very high velocity so that a dispersion of shale particles in steam is formed. Thus, a substantial degree of attrition and sintering of the shale particles occurs. Consequently, it is rather difficult to separate the product oil from the spent shale downstream of the reactor.